In general, as shown in FIG. 1, an armature acting as a rotator installed inside a motor comprises multiple cores 3 layered on a rotating shaft 2, a commutator 4 formed at one side of the rotating shaft 2, and a coil 5 wound around the core 3 and with its end thereof bonded to the commutator 4. The weight balance of an armature as constructed above is an important factor of the performance of a motor. If the weight distribution of the armature 1 is not uniform, it leads to a critical cause for the impedance of high-speed rotation, along with the irregular rotation, and the vibration and noise associated therewith.
Therefore, a balance measuring process using an armature balance machine is generally included in the entire manufacturing process of an armature. FIG. 2a is a schematic elevation view of a conventional armature balance machine. Referring to FIG. 2a, the construction of the conventional armature balance machine is described. The conventional armature balance machine includes a belt 30 for transferring the rotating power of a driving motor 22 to the outer peripheral surface of a core 3 of an armature 1, an armature driving device 20 having multiple rollers with the belt 30 wound therearound, a pair of v-blocks for supporting both end sides of a rotation shaft 2 of the armature 1, and a common measuring device 14 such as a piezoelectric element or a moving coil sensor for detecting the vibration of the armature 1 transferred from the v-block, thereby provide a balance measuring device 10.
On the other hand, in the conventional armature balance machine including the balance measuring device 10 and the armature driving device 20, various driving methods are currently used for drive the armature thereof, as shown in FIG. 2b. Among them, a belt driving method including a closed loop at both sides of D-type is most generally used for the automation machinery. In this method, replacement work of the armature to be measured is easy, and a balance measuring speed of stable range due is reached within a short time period to the big moment of inertia of the armature, resulting in a fast measurement of armature balance. Also, the belt is wound wrapping the both sides of the armature, thereby providing a wide contact area and thus enabling a stable and accurate measurement without a variation.
As one example of the above-described method, a construction of a typical armature driving device 20 of the armature balance machine is described in greater detail, referring to FIG. 2c. That is, a driving motor 22 with a driving roller connected thereto is mounted at one side of the bracket 21. Complementary rollers 34a, 34b are installed in the end of the upper side of the bracket 21, and a pair of fingers 24a, 24b which varies depending on the diameter of the core 3 of the armature 1 are formed. A tension adjusting mechanism 25 equipped with other complementary rollers 35 and other multiple complementary rollers are formed in desired positions of the bracket 21 and a belt 30 is wound around each roller 27, 28, 32, 34a, 34b, and 35. In the drawing, an unexplained reference numeral ‘C’ denotes a virtual centerline of the armature.